• Late Season Nitrogen Fertilizer for Cotton

      Knowles, Tim C.; Watson, Jack; Wakimoto, Vic; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1999)
      Field experiments were conducted during the 1996 and 1997 growing seasons in Mohave Valley to determine the effect of late season nitrogen (N) fertilizer applications on top crop yield potential of upland cotton. A long season production system utilizing late season nitrogen (N) applications through peak bloom (August) was compared to a short season production system in which N was applied through mid-bloom (June). Mid-season N applications were based on UA guidelines utilizing plant mapping and petiole nitrate data for the short season production system.
    • Cotton Fertility Study, Safford Agricultural Center, 1998

      Clark, Lee J.; Carpenter, E. W.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1999)
      Three different nitrogen fertilizer regimes were practiced in this study along with an unfertilized check. The same amount of nitrogen fertilizer was sidedressed in the plots in one, two or three applications. No significant differences were seen, but the trends looked like the split applications might have had some advantage.
    • Evaluation of an Acid Soil Conditioner in an Irrigated Cotton Production System

      Griffin, J. R.; Silvertooth, Jeffrey C.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1999)
      A single field study was conducted on a sodium-affected soil at the University of Arizona’s Maricopa Agricultural Center (MAC) in 1998. NuCotn 33B was dry planted and watered-up on 5 May 1998. Two treatments were evaluated; treatment 1 received no acid and treatment 2 received water-run acid applications. The acid used in this evaluation was sulfuric acid (H₂SO₄). The acid was applied at approximately 11 gallons acid/acre at each scheduled irrigation throughout the entire growing season. All other agronomic inputs and decisions were uniformly applied to both treatments in the same manner throughout the season. The experiment was arranged in a randomized complete block design with two treatments and six replications. Significant differences were found among the two treatments in terms of plant growth and soil water content (P<0.05). Lint yields were significantly different (P=0.0013) with the check having the highest yield.
    • Evaluation of Planting Date Effects on Crop Growth and Yield for Upland Cotton, 1998

      Norton, Eric R.; Silvertooth, Jeffrey C.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1999)
      A field study was conducted in 1998 at the University of Arizona Marana Agricultural Center (1,974 ft. elevation) to evaluate the effects of three planting dates on yield and crop development for three Upland varieties. Planting dates ranged from 9 April to 28 May and 342-885 heat units accumulated since Jan 1 (HU/Jan 1, 86/55o F thresholds). Crop monitoring revealed early season fruit loss leading to increased vegetative growth tendencies with all three planting dates. General trends also showed decreasing lint yield with the later dates of planting for all varieties. The more determinate variety (STV 474) was able to set and a fruit load more rapidly than the other varieties in this study at several dates of planting, which resulted in higher yields.
    • Defoliation of Pima Upland Cotton at the Safford Agricultural Center, 1998

      Clark, Lee J.; Carpenter, E. W.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1999)
      Nine defoliation treatments were applied to Pima and upland cotton to compare the treatment effects on percent leaf drop, trash sent to the gin, lint yields, percent lint turnout and percent first pick. All of the treatments were beneficial to leaf drop compared to the untreated check with the Ginstar treatments generally performing better than the others. The addition of nonionic surfactants and drift retardants seemed to reduce the activity of Ginstar. Yield differences on long staple treatments were notices and discussed in the paper.
    • Short Staple Variety Trial, Greenlee County, 1998

      Clark, Lee J.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1999)
      Six short staple cotton varieties including two New Mexico acalas varieties and one advanced strain, an Australian varieties and two SureGrow varieties with higher yield potential were tested in this study. New Mexico Acala 1517-95 had the highest lint yield with a yield of 419 pounds of lint per acre. The average yield was about 400 pounds per acre lower than the 6 year average due to a cold spring and a four inch rain that fell in one hour in the middle of July. In addition to lint yields; percent lint, plant heights, plant populations and lint hvi values are shown. A lint yield comparison for 1993 through 1998 is included in this paper.
    • Short Staple Regional Cotton Variety Trial, Safford Agricultural Center, 1998

      Clark, Lee J.; Carpenter, E. W.; Hart, G. L.; Nelson, J. M.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1999)
      Forty eight short staple varieties were grown in a replicated field trial on the Safford Agricultural Center. Excellent yields were recorded, especially considering the late start caused by unseasonably cold weather in April. FM 989, the Australian variety formerly known as IF 1003, produced the highest lint yield of 1601 pounds per acre. Three other varieties, FM 975, AP 4103 and IF 1002, produced over 1500 pound of lint per acre. Agronomic values for the plants at harvest and HVI data for lint quality are tabulated in this paper.
    • Nitrogen Management Experiments for Upland and Pima Cotton, 1998

      Silvertooth, Jeffrey C.; Norton, Eric R.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1999)
      Two field experiments were conducted in Arizona in 1998 at two locations (Maricopa and Marana). The Maricopa experiment has been conducted for nine consecutive seasons, the Marana site was initiated in 1994. The purposes of the experiments were to validate and refine nitrogen (N) fertilization recommendations for Upland cotton. The experiments each utilized N management tools such as pre-season soil tests for NO3 --N, in-season plant tissue testing (petioles) for N fertility status, and crop monitoring to ascertain crop fruiting patterns and crop N needs. At each location, treatments varied from a conservative to a more aggressive approach of N management. Results at each location revealed a strong relationship between the crop fruit retention levels and N needs for the crop. This pattern was further reflected in final yield analysis as a response to the N fertilization regimes used. The higher, more aggressive, N application regimes did not benefit yields at any location. In 1998, fruit retention levels were low and crop vigor was high. As a result, even slight increases in N fertilization and crop vigor translated into lower yield.
    • 1998 Demonstration Project of Arizona Irrigated Cotton Production

      Dittmar, Stefan H.; Ellsworth, Peter C.; Hartman, Philip MacD; Martin, Edward C.; McCloskey, William B.; Olsen, Mary W.; Roth, Robert L.; Silvertooth, Jeffrey C.; Tronstad, Russell E.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1999)
      The Demonstration project was conducted on the Demonstration Farm at the Maricopa Agricultural Center. In this project all current guidelines and recommendations disseminated by the University of Arizona were integrated in a systems approach. The management decisions were made by the Extension Specialists in agronomy, entomology, irrigation management, weed sciences, and plant pathology following the University recommendations. On a 50.5 acre field 80% Bt and 20% non-Bt cotton was planted dry and watered up. Due to the cold spring and sand-blasting, only a stand of 30,900 plants/A could be established with 84% terminal damage. 72 acreinches of water were used with 41.3 acre-inches in postplant irrigations. Weed control could be achieved with one preplant application and three cultivations. Three sprays against Lygus and one spray against whiteflies were necessary after the thresholds were exceeded. A total of 4120 lb seedcotton per acre were harvested, with 32.7% lint turnout (2.81 bales/A) and 45.9% seed turnout (1891 lb/A). After harvesting a field budget was established. The variable costs per acre were $915, the total cost $1266/acre. In spite of the lack of replications this project validates the usefulness and compatibility of University recommendations and the potential for integration of all disciplinary guidelines in one system.
    • Integrated Morningglory Control Strategies: Transgenic Cotton and Precision Cultivation

      Knowles, Tim C.; McCloskey, Bill; Wakimoto, Vic; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1999)
      A field demonstration was conducted in Mohave Valley to compare cotton morningglory control programs that combined the use of over the top herbicides Roundup Ultra on Roundup Ready cotton (Deltapine 436 RR) or Staple on non-transgenic cotton (SureGrow 125) with and without precision cultivation.
    • Monitoring Bemisia Susceptibility to Applaud (buprofezin) during the 1998 Cotton Season

      Ellsworth, Peter C.; Sieglaff, D. H.; Yazui, M.; Lublinkhof, J.; Silvertooth, Jeff; The University of Arizona, Department of Entomology & Maricopa Agricultural Center; Nihon Nohyaku, Ltd., Osaka, Japan; AgrEvo USA Co., Wilmington, DE (College of Agriculture, University of Arizona (Tucson, AZ), 1999)
      Starting in 1993, we developed a field-based protocol for bioassaying sweetpotato whiteflies (SWF) for susceptibility to buprofezin (Applaud®). Since then, we have monitored Arizona SWF populations (up to 5 regions) for susceptibility to Applaud in four out of the last six seasons. We observed no appreciable decrease in susceptibility. Instead, we have observed an increase in susceptibility of present day whiteflies when compared to populations bioassayed in 1993 and 1996, before any Applaud use in the U.S.. This result, however, is likely related to various procedural changes in the bioassay methodology. Nevertheless, our current estimates of whitefly susceptibility are similar to those obtained from various unexposed populations from around the world and to populations we bioassayed in 1997. Differences between our LC50 estimates and those of some other researchers can probably be explained by various procedural differences: 1) method of Applaud application, 2) whitefly stage collected and sources of leaf foliage, and 3) bioassay environmental conditions. Our results also showed each year that Applaud susceptibility does not decline after Applaud application(s) based on commercial paired field comparisons and replicated small and large plot evaluations. In fact, susceptibilities actually marginally increased after an Applaud application. This fact does not alter the recommendation for Arizona to limit Applaud use to one time per crop season, but does provide hope for the development of a sustainable use pattern even if usage continues on non-cotton hosts (i.e., on melons and vegetables under Section 18). Given the tremendous value of this mode of action, however, commodity groups should work together wherever possible to coordinate the usage of this and other valuable compounds so that whitefly generations are not successively exposed to this product.
    • Marana Pima Test

      Hart, G. L.; Nelson, J. M.; Barney, Glen; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1999)
      Seventeen pima cotton varieties were grown at the Marana Agricultural Center as part of the national cotton variety testing program. Lint yield, boll size, lint percent and fiber properites are presented in this report.
    • Mortality Factors Affecting Whitefly Populations in Arizona Cotton Management Systems: Life Table Analysis

      Naranjo, Steven E.; Ellsworth, Peter C.; Silvertooth, Jeff; USDA-ARS, Western Cotton Research Laboratory, Phoenix, AZ and 2University of Arizona, Maricopa, AZ (College of Agriculture, University of Arizona (Tucson, AZ), 1999)
      Direct-observation studies were conducted in replicated experimental plots to identify causes and estimate rates of mortality of whiteflies in cotton over the course of six generations from late June through late October. In plots receiving no whitefly or Lygus insecticides, predation and dislodgment were major sources of egg and nymphal mortality, and overall survival from egg to adult ranged from 0-18.2%. Similar patterns were observed in plots treated with the insect growth regulator (IGR) Knack. Applications of the IGR Applaud or a mixture of endosulfan and Ovasyn caused high levels of small nymph mortality and reduced rates of predation on nymphs during the generation immediately following single applications of these materials in early August. Whitefly populations declined to very low levels by mid-August in all plots, and few differences were observed in patterns of whitefly mortality among treated and control plots 4-6 weeks after application. The population crash was associated with an unknown nymphal mortality factor which reduced immature survivorship during this first posttreatment generation to zero. The application of insecticides for control of Lygus in subplots modified patterns of mortality in all whitefly treatments by generally reducing mortality from predation during generations observed from mid-July through August. Parasitism was a very minor source of mortality throughout and was unaffected by whitefly or Lygus insecticides.
    • How to Obtain Cotton Advisories from the Internet

      Brown, P.; Russell, B.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1999)
      Weekly advisories developed by the Arizona Cotton Advisory Program are now available from the Internet. Nineteen location-specific advisories are developed each Monday morning and then transferred to the Main AZMET Internet Web Page located at URL address http://ag.arizona.edu/azmet. To retrieve advisories from the Internet users must 1) log on to the Internet using the procedures required by your Internet service provider; 2) enter the URL for the Main AZMET Web Page; 3) move to the Cotton Advisory sub-page; and 4) select the advisory of interest. Advisories for the most recent week, this year to date, and all of 1998 are available at this Internet address.
    • Pima Regional Variety Test at the Maricopa Agricultural Center, 1998

      Hart, G. L.; Nelson, J. M.; Clark, Lee J.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1999)
      Seventeen Pima varieties were grown in a replicated trial at the Maricopa Agricultural Center as part of the national cotton variety testing program. Lint yield, boll size, lint percent, plant populations, plant heights and fiber properties are presented in this report.
    • 1998 Cottonseed Variety and Fungicide Evaluation

      Knowles, Tim C.; Odom, Bruce; Wakimoto, Del, 1947-; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1999)
      Two upland cotton varieties (Deltapine 5415 and SureGrow 125) were subjected to various seed fungicide treatments to determine seedling emergence and vigor in a Mohave Valley field prone to Rhizoctonia infection of cotton seedlings. During 1998, cotton seedlings in this field exhibited symptoms associated with Rhizoctonia, Pythium, and Thielaviopsis fungi. Of the treatments examined in this study, Baytan+Thiram+Allegiance or Baytan+Ascend+Allegiance cotton seed treatments provided superior seedling disease protection. The Protégé+Allegiance fungicide treatment provided superior seedling disease protection when applied to Deltapine 5415 cotton seed, however seedling disease suppression was poor when the same treatment was applied to SureGrow 125. The Vitavax-PCNB+Allegiance and NuFlow M+Maxim+Apron were the least effective fungicide seed treatments examined in this study.
    • Open Cotton Boll Exposure to Whiteflies and Development of Sticky Cotton

      Henneberry, Tom J.; Forlow Jech, L.; Hendrix, D. L.; Brushwood, D.; Steele, T.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1999)
      Trehalulose and melezitose produced by Bemisia argentifolii Bellows and Perring and thermodetector counts in cotton lint increased with increasing numbers of days of exposure of open cotton bolls in infested cotton plots. Thermodetector counts were significantly correlated to amounts of trehalulose and melezitose. Rainfall of 0.5 inch reduced trehalulose and melezitose in cotton lint within 5 h following the rain. The results suggest dissolution of the sugars followed by runoff as opposed to microbial degradation.
    • Agronomic Evaluations of Transgenic Cotton Varieties, 1998

      Silvertooth, Jeffrey C.; Norton, Eric R.; Silvertooth, Jeff; University of Arizona (College of Agriculture, University of Arizona (Tucson, AZ), 1999)
      Several field experiments were conducted in many of the cotton growing areas of Arizona in 1998 for the purpose of evaluating agronomic characteristics of many new transgenic Upland cotton varieties. In many cases, the new transgenic lines were compared directly with their recurrent (nontransgenic) parents. Evaluations were carried out by collecting plant mapping data from each variety on a regular 14 day interval throughout the season and relating the resultant information to established baselines for Upland cotton in Arizona. Lint yield measurements were also taken on each variety at all locations. Results indicate that all transgenic lines tested are very similar to their recurrent parents in terms of growth, development, and yield. Some subtle differences were noted but they were very slight and should not impact management of the varieties significantly in comparison to their recurrent parents.
    • Upland Regional Cotton Variety Test at the Maricopa Agricultural Center, 1998

      Hart, G. L.; Nelson, J. M.; Clark, Lee J.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1999)
      Thirty six upland cotton varieties were grown at the Maricopa Agricultural Center as part of the national cotton variety testing program. Lint yield, boll size, lint percent, plant populations, plant heights and fiber properties are presented in this paper.
    • Systemic Insecticide Applications at Planting for Early Season Thrips Control

      Knowles, Tim C.; Bushong, Neil; Lloyd, Jim; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1999)
      Temik 15G (6 lbs/acre) or Thimet 20G (8.2 lbs/acre) granular insecticides were applied to 40 inch rows in furrow at planting to cotton growing in Parker Valley, AZ. Moderate thrips pressure (0.5-1.5 thrips/plant) was experienced for the first eight weeks after planting and granular insecticide application. Temik provided better thrips control than Thimet for the first seven weeks after planting this study. Thrips control was similar for the two insecticides beyond eight weeks after planting. Temik application resulted in higher fruit retention levels measured up to 10 weeks after planting, compared to Thimet. However, fruit retention levels measured from 12 to 16 weeks after planting were similar for both Temik and Thimet when cotton plants compensated for early season square losses caused by thrips feeding.